Final results from the Nebraska Secretary of State showed Sasse with 49.3 percent, well ahead of banker Sid Dinsdale with 22 percent and former state Treasurer Shane Osborn at 21 percent.

“What a great victory for Ben Sasse, and all the freedom-loving people of Nebraska,” said Tea Party Patriots Citizens Fund Chairman Jenny Beth Martin. “He never waivered in his support for personal freedom, economic freedom and a debt-free future.”

In West Virginia, former Maryland Republican Chairman Alex Mooney, with strong backing from conservative groups, won the GOP nomination for that state's Second District congressional seat.

The victories came a week after the tea party candidate for the Republican Senate nomination in North Carolina was soundly defeated--and a week before Georgia, Kentucky and Idaho feature congressional races where tea party candidates vie with Republican establishment hopefuls.

In each of the three states, the tea party candidates are underdogs.

What is the tea party?

A loosely-knit — some would say not knit at all — series of organizations across the country usually dedicated to reducing federal debt and slowing the growth of government — or shrinking it. There’s no centralized organization and no real structure, making it hard to easily characterize or even identify who’s powerful or who’s behind the movement. Its origins are often traced to CNBC journalist Rick Santelli, who in February 2009 was angry about a government mortgage refinancing plan. He recommended a “tea party” for the Chicago River.